Hello, i recently built my own computer, the components are as follows: CPU: AMD x4 ii 955 PSU: cit 750watt (dual rail 21 amp each) GPU: ati saphire radeon 5570 1gb ddr3 Motherboard: ASrock 870 extreme 3 RAM: 16GB corsair vengeance HDD: Seagate Barracuda 1.5tb sata III(but i use sata II cable) OS: windows 7 ultimate 64bit on first boot everything was fine, it worked well and still does but the problem is turning it on. sometimes when I click the power button it doesn't turn on (the fans spin a little and LED's turn on for a very short time then everything stops, if I then click the power button again nothing at all happens.) to overcome this problem I have to unplug 24pin and 8pin power from motherboard and turn off the PSU from the back, I then wait a little, turn the PSU on put the 24 and 8pin to the motherboard and then press the power button, even this does not work sometimes. I have replaced the PSU already, the power button is also fine and is not stuck so is the reset button. I can't work out the problem with my computer, if anybody knows what the problem is please help. By the way I'm new to this site. also this only seems to happen when I leave my speakers turned on, or if I leave the computer in sleep mode for a while with the power LED flashing this only happens sometimes. is it just my cheap power supply? thanks in advance.